The tropical Pacific is experiencing one of the fastest-developing El Niño events on record as 2026 progresses through its second half. The phenomenon, which releases oceanic heat into the atmosphere and alters global weather patterns, has significantly shifted expectations for annual global temperatures.
Temperature data from six major monitoring organizations shows the first half of 2026 was the third-warmest on record, trailing only 2024 and 2025. January began relatively cool due to lingering weak La Niña conditions, but each subsequent month ranked progressively higher in historical records. May and June both achieved the second-warmest temperatures for those respective months, exceeded only by their 2024 counterparts. Copernicus additionally reported that global sea surface temperatures over ice-free oceans set a new June record.
The El Niño’s intensity is developing at an unprecedented pace. The key measure of El Niño strength, the Niño3.4 index in the tropical Pacific, crossed the 0.5C threshold in April, reached 1C in May, hit 1.6C in June, and exceeded 2C in early July. This progression represents one of the fastest onsets documented in observational records. Forecast models from 14 different groups analyzing 667 model runs suggest the event could peak between July and December with temperatures reaching 3.59C on average, with over 91 percent of runs predicting the strongest El Niño in the modern record.
Weather patterns in the first half of 2026 reflected the developing El Niño, with the largest warm temperature anomalies concentrated in the Arctic, western Europe, the western United States, and parts of Asia. More than 30 percent of global surface area experienced top-five warmest conditions for the first half of the year. A particularly severe European heatwave in late June broke numerous national heat records and resulted in thousands of deaths. Western Europe recorded its hottest June on record, with France reaching 44.3C and the United Kingdom hitting 37.3C on three consecutive days.
Based on observed temperatures and current El Niño forecasts, Carbon Brief projects 2026 will average approximately 1.51C above pre-industrial levels, potentially making it the second-warmest year on record after 2024. The probability of 2026 setting a new annual record has risen from 19 percent in April to 35 percent in mid-July, driven almost entirely by strengthening El Niño predictions rather than observed temperature increases. Projections for 2027, when the peak warming effects of the El Niño typically manifest, show a 92 percent chance of setting a new record with an estimated temperature of 1.71C above pre-industrial levels.
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